It is common practice to provide pagers which emit an audible tone indicating that a particular recipient is to receive a message. Thereafter, the message is transmitted via voice communication to the recipient whether or not this recipient is ready to receive the message. As a result, the content of the message is sometimes lost when the recipient either cannot remember the content of the message or a pencil and paper is not immediately available to transcribe the message. This is particularly severe when telephone numbers or addresses are transmitted. The result is frustration of the recipient and the necessity of communicating with the originator of the message to obtain its content. In one broad aspect this invention alleviates the inconvenience of the prior art paging systems by providing storage and recall of the transmitted message through the use of a precessing display of a stored message (soft copy unit) in an unattended unit.
In another broad aspect of this invention a portable encoder unit is coupled via a telephone link to a common carrier paging transmitter. The system is compatible with existing transmitters and permits the encoding of messages anywhere that telephone service is available. It is a feature of the subject invention that the encoded message may be transmitted through the common carrier transmitter audio channel as a substitute for voice communication without alteration of existing unattended transmitting equipment. In this regard, in one embodiment the encoder includes a message entry keyboard and means for converting the entered message into a series of audio tones for transmission on the audio channel after the transmitter has automatically sent a predetermined address code, responsive to the dialed telephone number. Thus no additional message encoding apparatus or tone generating equipment is necessary at the common carrier transmitter. In one embodiment the encoding unit may include a precessing display for message editing and review prior to transmission, or alternatively, other types of editing displays may be used.
As illustrated in U.S. Pat. No. 3,846,783 issued to Aspell et al. on Nov. 5, 1974, it is known to provide a pager with a hard copy printout. While the Aspell patent describes generally the use of light emitting diodes or liquid crystals for displaying a message, the subject invention provides, in one embodiment, for a precessing display which rolls by characters across a limited field. This type display permits the display of messages which have a greater length than the display by precessing the message across the display.
In one embodiment the pager utilizes a ROM-driven LED dot matrix display fed by a recirculating shift register memory which generates the precession as it recirculates. In another aspect of the subject invention the LED display enables the presentation of the message in the dark a portion at a time. In the subject soft copy pager, the message is stored in the pager's memory and may be recalled at the convenience of the recipient by a precessing alpha/numeric display so that the information contained in the message can be made available at the convenience of the recipient. In a further embodiment the soft copy pager is provided with encoding means so that a message can be composed on the soft copy unit prior to its transmittal to a high power transmitter for transmission to another paging unit.
It is therefore an object of this invention to provide an improved hand held paging system in which a message transmitted to a recipient is stored at the pager for readout at the convenience of the recipient.
It is another object of this invention to provide a pager which is inexpensive, silent and displays a message in alpha/numeric form a portion at a time.
It is a further object of this invention to provide a method of transmitting a message in which the message is stored at a remote location in a memory and in which the message is recalled by the recipient at his convenience through the use of a precessing display.
It is another object of this invention to provide a precessing display pager in which the precession is generated by a recirculating shift register.
It is a still further object of this invention to provide a soft copy pager which may be utilized both for the receipt of a transmitted message and for the encoding of a message to be transmitted thereby combining in one unit the two functions.
It is a yet still further object of this invention to provide a paging system in which messages may be locally encoded and transmitted on the audio channel of existing unattended common carrier transmitting equipment .